In many cities in China, rivers and lakes are severely polluted, causing a loss of 37.7 billion yuan. Therefore, sludge treatment of urban rivers and lakes is imminent. Nevertheless, there is no good treatment measure to improve the sludge water of rivers and lakes into ecological water system. Moreover, due to high water content and large transport volume of sludge, centralized treatment is required when the sludge is in solid state after local dehydration for volume reduction. Calculated as per 80% of water content, the total sludge water yield will soon break through 30 million tons, imposing a very rigorous situation of sludge treatment.
Therefore, it is necessary to develop the solutions to improving sludge water into ecological water system.